Secondary clock movement



April 15, 1930. R. s'. FULTON 1,754,508

SECONDARY CLOCK MOVEMENT Filed Dec. 1; 1924 L 2 7 27 C Z5 it Ear-11:15

Patented Apr. 15, 1930 UNITED STATES PATENT OFFICE ROLLAND S. FULTON, OF DETROIT, MICHIGAN, ASSIGNOR TO TIME SYSTEMS COMPANY, A CORPORATION OF MICHIGAN SECONDARY CLOCK MOVEMENT Application filed December 1, 1924. Serial No. 753,243.

This invention relates generally to electric clock systems and particularly to secondary movements for use in such systems, and has for its object, the construction of a secondary movement of this character that will be operative by an alternating current and at the same time accurately operate under the con trol of the master clock of the system.

\Vith the above and other objects in view,

as will be apparent, this invention consists in the construction, combination and arrangement of parts all as hereinafter more fully described, claimed and illustrated in the accompanying drawing, wherein Figure 1 is a rear elevation of a secondary clock movement embodying the present invention.

Figure 2 is a longitudinal section taken through the operating magnet thereof.

As is well known, anelectrical clock system includes a master clock and any number of secondary clocks all connected withthemaster clock, so that as the latter makes contact at predetermined intervals, the relays control- 25 ling the movements ofthe secondary clocks are operated to close the main circuit of the system whereby the magnets or relays of the individual secondary clocks are energized to advance the secondary clock movements the pre- 30 determined amount. Heretofore, such systems have been operated by the use of direct current for the reason that the frequency of alternating current would cause oscillation of the relays or magnets of the secondary clock 5 movements and the consequent gain-by the secondary clocks, thereby destroying or at least greatly reducing the accuracy of the entire system. The present invention is designed to provide a secondary clock movement which may operate by alternating current and at the same time eliminate all oscillation due to the frequency of the alternating current and thus maintain the accuracy of the system.

Referring more particularly to the drawa ing, 10 designates the rear face of the dial plate of a secondary clock upon which the entire secondary movement is mounted. A

spider supporting frame 11 is secured to the plate 10 and held spaced therefrom by the screws 12 operating through the ends of the fingers of the frame 11 and engaging posts (not shown in the drawing) interposed between sald fingers and the dial plate 10. The usual secondary clock gear train mechanism 14 controls and operates the hands of the secondary clock located on the opposite side of the dial plate 10 to the clock mechanism 13.

An escapement lever 15 is pivoted as at 16 to one of the fingers of the frame 11 and carries an escapement pawl 17 pivoted as at 18 to its outer end. This pawl 17 has a tooth 19 pivoted at its free end to ride over and en age the teeth of the escapement wheel 14. Vi hen the end of the escapement lever 15 carrying the pawl 17 is elevated, the tooth 19 thereof rides over the teeth of the escapement wheel 14'and when it is lowered the tooth 19 of the pawl engages one of the teeth of the wheel 14 moving the latter until the end of the downward path of movement of the lever 15 and pawl 17 is reached. Thus the hands of the secondary clock are advanced.

The end 20 of the escapement lever 15 opposed to pawl 17 merges into a transverse cross-bar or armature 21 for cooperation with the secondary magnet or relay by means of which the end of the lever 15 carrying the pawll? is elevated and released to return to its normal position after the operation of the escapement wheel 14. Attached to the crossbar or armature 21 by means of the screw 22 are the secondary or retarding cores 28 of iron or other suitable material. The retarding cores 23 reciprocate in the upper ends of the coils 24 and when at the extreme end of their movement into the coils 24, extend only partly therethrough. The coils 24 are preferably of low resistance and are insulated, being mounted on shells 25 of non-magnetic material protruding from the coils 24 at the ends thereof. Mounted at the lower end of the shells 25 and recessed to receive said shells is the iron core plate 26 to which are secured the cores 27 by means of the screws 28. These cores extend partly through the coils 24 and are laminated.

By having retarding cores 23 secured to the armature or crossbar 21 and extendmg partly through or into the coils 24, the escapement lever has a high moment of inertia not readily overcome by the frequency of the current and the coils through which the cores 23 pass can- 5 not be demagnetized quickly enough to permit the cross-bar or armature 21 to oscillate due to the frequency of the current. The

laminations in the primary cores 27 eliminates residual magnetism which might assist in causing the oscillation or operation of the device resulting in a gain in the secondary clock.

A shunt choke coil 29 is mounted on the terminal block 30 to prevent any counter-electromotive force generated from other movements on the line from surging back When the circult is broken, thereby advancing the secondary clock mechanism.

Vhat is claimed is:

In a secondary clock mechanism for operalion on commercial alternating current supply lines and having a pivoted escapement lever, a solenoid for connecting to an alternating current supply, a core in the solenoid, metallic rod retarding means connected to the escapemen-tlever and extending into the solehold to coact therewith, and current-surgeabsorbing means connected in parallel With the solenoid.

In testimony whereof I have hereunto subscribed my name.

ROLLAND S. FULTON. 

